Catheter having a multi-section tubular member and method of making the same

ABSTRACT

A multi-section tubular member including a sleeve surrounding and bridging a joint between a first section and a second section of the tubular member, and a method of forming a multi-section tubular member are disclosed. A polymeric sleeve may extend over a portion of the first section and an adjoining portion of the second section. A length of heat shrink tubing may be placed over the sleeve and heated, thereby compressing the heat shrink tubing around the sleeve. The sleeve may then be thermally bonded to each of the first section and the second section. The heat shrink tubing may then be removed, leaving the sleeve securely joining the first section and the second section to form a multi-section tubular member.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/279,985 filed Apr. 17, 2006

TECHNICAL FIELD

The invention generally relates to medical devices. More specifically,the invention relates to a medical device, such as a catheter, includinga multi-section tubular member, and methods of joining multiple sectionsof a tubular member.

BACKGROUND

Elongated medical devices are commonly used to facilitate navigationthrough and/or treatment within the anatomy of a patient. A variety ofelongate medical devices for intracorporeal use, such as catheters,endoscopes, guidewires and the like, have been developed over the pastseveral decades. Because the anatomy of a patient may be very tortuous,it is often desirable to combine a number of performance features insuch devices. For example, it is sometimes desirable that the devicehave a relatively high level of pushability and torqueability,particularly near its proximal end. It is also sometimes desirable thata device be relatively flexible, particularly near its distal end.

A number of different elongated medical device structures and assembliesare known, each having certain advantages and disadvantages. However,there is an ongoing need to provide alternative elongated medical devicestructures, assemblies, and methods.

One such elongate medical device, a balloon catheter, can include aninflatable and deflatable balloon carried by a long narrow catheterbody. The balloon is initially folded around the catheter body to reducethe radial profile of the balloon catheter for easy insertion into thebody. During use, the balloon may be inflated and later deflated at aselected location within the body.

One common balloon catheter design includes a coaxial arrangement of aninner tubular member surrounded by an outer tubular member. The innertubular member typically includes a lumen that can be used for deliveryof the device over a guidewire. The annular space between the innertubular member and the outer tubular member typically defines aninflation lumen in fluid communication with the balloon, wherein aninflation fluid passes through during inflation and deflation of theballoon. It is important that the inflation lumen remain substantiallyopen and unobstructed during inflation and deflation of the balloon toinsure proper inflation and deflation of the balloon.

Some such catheters may utilize tubular members having multiple sectionsof dissimilar materials joined together by thermally bonding thesections together to provide regions of varying flexibility. There is anongoing need to provide new structures and methods of joining multiplesections of a catheter shaft without compromising the desiredcharacteristics of the catheter shaft.

SUMMARY

The invention is directed to elongate medical devices, such ascatheters, having one or more multi-section tubular members and methodsof forming the same. The one or more sections may be joined togetherwith a polymeric tubular sleeve, while maintaining the low profile ofthe tubular member or other advantageous attributes of the tubularmember.

Accordingly, one embodiment of the invention is a balloon catheterhaving an outer tubular member, an inner tubular member, and aninflatable balloon. The inner tubular member may include a first,proximal section and a second, distal section. The proximal section mayabut the distal section, and a polymeric sleeve may be used to securethe proximal section to the distal section, thus forming a joint betweenthe proximal section and the distal section.

Another aspect of the invention is a method of forming a multi-sectiontubular member for use in an elongate medical device. A first tubularsection and a second tubular section of a tubular member are placedlongitudinally end-to-end, such that an end of the first tubular memberabuts the end of the second tubular member, wherein the region ofabutment defines a junction between the first and second tubularmembers. A polymeric tubular sleeve is then placed over the first andsecond sections such that the sleeve extends proximally and distallyfrom the junction between the first and second tubular members. A lengthof tubing, such as heat shrink tubing, is placed over and surrounds thepolymeric sleeve. Thermal energy is applied to the heat shrink tubing tocompress the heat shrink tubing around the sleeve and tubular members.Thermal energy is applied to the polymeric sleeve, elevating thetemperature of the sleeve and the adjacent surface of the correspondingportion of the tubular members, thereby creating a bond between thepolymeric sleeve and each of the first tubular member and the secondtubular member. The heat shrink tubing is then removed from the tubularmembers and sleeve.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments in connection withthe accompanying drawings, in which:

FIG. 1 is a plan view of an illustrative balloon catheter in accordancewith the invention;

FIG. 2 is a cross-sectional view of a portion of the illustrativeballoon catheter of FIG. 1;

FIG. 3A is a cross-sectional view taken along line 3A-3A of FIG. 2;

FIG. 3B is a cross-sectional view taken along line 3B-3B of FIG. 2;

FIGS. 4-8 illustrate a method of joining two tubular segments inaccordance with the invention; and

FIG. 9 is a cross-sectional view of two tubular segments joined togetherwith a sleeve in accordance with the invention.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the term “about” may be indicative asincluding numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

Although some suitable dimensions of various embodiments are disclosedherein, one of skill in the art would understand that desired dimensionsmay deviate from those expressly disclosed, unless clearly stated to thecontrary.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The detailed description and the drawings, which are notnecessarily to scale, depict illustrative embodiments and are notintended to limit the scope of the invention. The illustrativeembodiments depicted are intended only as exemplary. Selected featuresof any illustrative embodiment may be incorporated into an additionalembodiment unless clearly stated to the contrary.

Refer now to FIG. 1, which illustrates a catheter 10 in accordance withone example embodiment. The catheter 10 may be one of a variety ofdifferent catheters, but is preferably an intravascular catheter.Examples of some exemplary intravascular catheters includemicrocatheters, drug delivery catheters, diagnostic catheters, guidecatheters, balloon catheters, stent delivery catheters, embolic coildelivery catheters, and atherectomy catheters. FIG. 1 illustrates aballoon catheter having a proximal end 15 and a distal end 17. Ingeneral, the catheter 10 may include a generally elongate shaft 12. Ahub assembly 18 may be coupled to the proximal portion 14 of theelongate shaft 12 and an inflatable balloon 20 may be coupled to thedistal portion 16 of the elongate shaft 12.

The elongate shaft 12 may have a length and an outside diameterappropriate for its desired use, for example, to enable intravascularinsertion and navigation. For example, in some embodiments, the elongateshaft 12 may have a length in the range of about 1 to about 300 cm ormore, or in some embodiments in the range of about 20 to about 250 cm,and an outside diameter in the range of about 1 F (French) to about 20F, or in some embodiments, in the range of about 1 F to about 10 F.

The catheter 10 may be an over-the-wire (OTW) type catheter or thecatheter 10 may be a single-operator-exchange (SOE) type catheter, forinstance. Typically, an OTW catheter is configured such that a guidewiremay extend within a lumen of the elongate shaft 12 substantially theentire length of the catheter 10. On the other hand, a SOE catheter istypically configured with a distal guidewire port 25 proximal of theballoon 20, but distal of the proximal end 15 of the catheter 10. (It isnoted that the guidewire port 25 shown in FIG. 1 is typically notpresent in an OTW type catheter). The guidewire port 25 provides anopening in the elongate shaft 12, such that a guidewire (not shown) mayextend within a lumen of the elongate shaft 12 through a distal regionof the catheter 10, but may be located exterior of the elongate shaft 12throughout a proximal portion of the catheter 10.

FIG. 2 shows a partial cross-sectional view of a portion of the elongateshaft 12. The portion of the elongate shaft 12 shown in FIG. 2 may be aportion of the elongate shaft 12 located proximal of the balloon 20.However, in other embodiments, the portion of the elongate shaft 12, asshown in FIG. 2, may be located at a different position along thecatheter 10. For instance, the portion shown in FIG. 2 may be locatedbeneath the proximal waist of the balloon 20 or may be located beneath amidsection of the balloon 20. The elongate shaft 12 may include an outertubular member 40 and an inner tubular member 50 extending through atleast a portion of the outer tubular member 40. In the case of anover-the-wire type (OTW) catheter, the inner tubular member 50 mayextend through substantially the entire length of the outer tubularmember 40, from the proximal portion of the elongate shaft 12 to thedistal portion of the elongate shaft 12. Thus, a guidewire may beinserted through the inner tubular member 50 and extend substantiallythe entire length of the elongate shaft 12. In the case of asingle-operator-exchange type (SOE) catheter, the inner tubular member50 may extend through a distal portion of the outer tubular member 40,from the guidewire port 25 to the distal end of the catheter. Thus, aguidewire may be inserted through the guidewire port 25 into the innertubular member 50 and extend to the distal end of the elongate shaft 12.In a SOE catheter, the inner tubular member 50 may not be present in theproximal portion of the elongate shaft 12.

In some embodiments, the distal end of the outer tubular member 40 maybe secured to the proximal waist of the balloon 20 and the inner tubularmember 50 may be coaxially disposed in the outer tubular member 40 andmay extend distal of the distal end of the outer tubular member 40through the balloon 20 such that the distal end of the inner tubularmember 50 is secured to the distal waist of the balloon 20. The balloon20 may be secured to the tubular members 40, 50 by laser bonding, RFbonding, adhesive, or other means known in the art.

The inner tubular member 50 may have an inner surface 30 and an outersurface 32. The inner surface 30 may define a lumen 34, for example aguidewire lumen. The inner tubular member 50 may be coaxial with theouter tubular member 40, such that the space between the outer surface32 of the inner tubular member 50 and the inner surface 36 of the outertubular member 40 defines a lumen 38, for example an annular inflationlumen. The inflation lumen 38 may be in fluid communication with theballoon 20 and the hub assembly 18.

The inner tubular member 50 may include a first, proximal section 50Aand a second, distal section 50B. When describing the first section 50Aas a proximal section and the second section 50B as a distal section,the intention is to describe the first section 50A as being locatedproximal of the second section 50B. It is not the intention to imply theproximal section 50A is necessarily located in the proximal portion 14of the catheter 10, although in some embodiments that may be the case.The proximal section 50A may be a single layer or a multi-layeredtubular member. The proximal section 50A may include 1, 2, 3, 4, 5, 6 ormore layers. The distal section 50B may be a single layer or amulti-layered tubular member. The distal section 50B may include 1, 2,3, 4, 5, 6 or more layers. Additionally, the intention is not to limitthe inner tubular member 50 as having only two distinct sections, but insome embodiments, the inner tubular member 50 may include additionalsections as desired, which may or may not be similarly joined togetheras described herein. For example, the inner tubular member 50 mayinclude three, four, five or more distinct tubular sections joinedtogether.

The proximal end of the distal section 50B and the distal end of theproximal section 50A may be positioned end-to-end, in an abuttingorientation, or in another joining orientation. The interface betweenthe proximal section 50A and the distal section 50B defines a joint 65.Although the joint 65 shown in FIG. 2 is a butt joint, the joint mayalternatively be an overlapping joint, tapering joint, or the like. Apolymeric tubular sleeve 60 may be disposed over the joint 65 and mayextend proximally of the joint 65 for a length and distally of the joint65 for a length. Thus, the sleeve 60 may bridge the joint 65. The sleeve60, in the embodiment shown, desirably has a low profile, thus notappreciably obstructing the annular inflation lumen 38.

Although the joint 65 is shown in FIGS. 1 and 2 to be located proximalof the balloon 20, in some embodiments, the joint 65 joining twosections of the inner tubular member 50 may be located at a locationunderlying the proximal waist of the balloon 20 or the joint 65 may belocated at a location underlying the body of the balloon 20.Alternatively, the location of the joint 65 may be located at anotherposition along the catheter 10.

The sleeve 60 may be desirably formed of a thin, thermoplastic material.Some example materials may include, but are not limited to, polyamide,polyether block amide, polyurethane, silicone rubber, nylon,polyethylene, fluorinated hydrocarbon polymers, and the like. Forexample, in some particular examples the sleeve 60 is 100% polyamide 6,polyamide 12, or thermoplastic polyurethane. Some polymer materialssuitable for use in the sleeve 60 are sold under the trademarks ofPEBAX, PELLETHANE, TEXIN and VESTAMID.

The sleeve 60 may be formed by extrusion, drawing, injection molding,blow molding, or the like. In some embodiments, the sleeve 60 may beformed of a polymeric material having highly oriented molecular chains.In some embodiments, the molecular chains of the sleeve 60 may be highlyoriented in a longitudinal direction. In other words, the molecularchains may be longitudinally aligned with one another along thelongitudinal axis of the sleeve 60. Thus, the molecular chains may bearranged and stretched in a longitudinal orientation. Such anorientation may provide the sleeve 60 with increased tensile strength.In some embodiments, the molecular chains of the sleeve 60 may be highlyoriented in a circumferential direction. In other words, the molecularchains may be circumferentially aligned with one another around thecircumference of the sleeve 60. Thus, the molecular chains may bearranged and stretched in a circumferential orientation. Such anorientation may provide the sleeve 60 with increased hoop strength. Insome embodiments, the molecular chains of the sleeve 60 may be highlyoriented in a helical direction. In other words, the molecular chainsmay be helically aligned with one another to form a helix along thelength of the sleeve 60. Thus, the molecular chains may be arranged andstretched in a helical orientation. Such an orientation may provide thesleeve 60 with increased torsional strength.

FIG. 3A shows a cross-sectional view of the catheter shaft 12 takenalong line 3A-3A of FIG. 2. The proximal section 50A of the innertubular member 50 shown in FIG. 3A is a multi-layer section shown as atri-layer section having three layers; an inner layer 52A, an outerlayer 54A, and an intermediate or tie layer 56A interposed between theinner layer 52A and the outer layer 54A. However, in other embodiments,the proximal section 50A of the inner tubular member 50 may be a singlelayer tubular member, a bi-layer tubular member, or other multi-layeredtubular member.

FIG. 3B shows a cross-sectional view of the catheter shaft 12 takenalong line 3B-3B of FIG. 2. The distal section 50B of the inner tubularmember 50 shown in FIG. 3B is a multi-layer section shown as a tri-layersection having three layers; an inner layer 52B, an outer layer 54B, andan intermediate or tie layer 56B interposed between the inner layer 52Band the outer layer 54B. However, in other embodiments, the distalsection 50B of the inner tubular member 50 may be a single layer tubularmember, a bi-layer tubular member, or other multi-layered tubularmember.

In both, the proximal and distal sections 50A, 50B, the inner layer 52A,52B may include a lubricious polymer having a low coefficient offriction to facilitate advancement of a guidewire therethrough. In someembodiments, the inner layer 52A, 52B may be formed of high radialstrength, hard, low-friction polymer that resists collapse duringballoon inflation and facilitates movement of the catheter over aguidewire. Some suitable polymers include high density polyethylene(HDPE), or a fluorocarbon-based polymer, such as polytetrafluoroethylene(PTFE) or a copolymer of tetrafluoroethylene with perfluoroalkyl vinylether (PFA) (more specifically, perfluoropropyl vinyl ether orperfluoromethyl vinyl ether), or the like, or graphite-filled nylons.One particular example of a high density polyethylene is Marlex 4903,available from Chevron Phillips.

The intermediate layers 56A, 56B of the proximal and distal sections50A, 5013 of the inner tubular member 50 may be a tie layer thatfacilitates bonding between the inner layer 52A, 52B and the outer layer52A, 52B of each of the proximal and distal sections 50A, 50B. Somesuitable polymers for the intermediate layer 56A, 56B include maleicanhydride functionalized linear low-density polyethylene. One example ofwhich is Plexar PX-380, available from Equistar, Houston, Tex.

The material for the outer layers 54A, 54B of the inner tubular member50 may be selected for their individual mechanical characteristics, suchas pushability and/or trackability. The material chosen for the outerlayer 54A of the proximal section 50A may be a stiffer material than thematerial chosen for the outer layer 54B of the distal section 50B.However, in some embodiments, it may be desirable that the materialchosen for the outer layer 54A of the proximal section 50A is moreflexible than the material chosen for the outer layer 54B of the distalsection 50B. The flexibility or stiffness of a polymer may becharacterized by its flexural modulus, which is the ratio of stress tostrain in flexural deformation. In some embodiments, the flexuralmodulus of the outer layer 54B of the distal section 50B is about 75%less than or more than 75% less than the flexural modulus of the outerlayer 54A of the proximal section 50A. In some embodiments, the flexuralmodulus of the distal outer layer 54B is about 15 to about 500 MPa andthe flexural modulus of the proximal outer layer 54A is about 700 toabout 4000 MPa.

Some examples of suitable polymers may include, but are not limited to,elastomers, such as thermoplastic elastomers, polyoxymethylene (POM),polybutylene terephthalate (PBT), polyether block ester, polyether blockamide (PEBA), fluorinated ethylene propylene (FEP), polyethylene (PE),polypropylene (PP), polyvinylchloride (PVC), polyurethane,polytetrafluoroethylene (PTFE), polyether-ether ketone (PEEK),polyimide, polyamide, polyphenylene sulfide (PPS), polyphenylene oxide(PPO), polysulfone, nylon, perfluoro(propyl vinyl ether) (PFA),polyether-ester and their copolymers, blends, mixtures or combinationsthereof. Some examples include polyamides such as polyamide 12, andblends thereof.

For instance, in some embodiments, the proximal outer layer 54A may be ablend of about 40% to about 70%, or about 45% to about 60%, by weight ofan amorphous polyamide, such as amorphous polyamide 12, and about 30% toabout 55%, or about 40% to about 55%, by weight of a non-amorphouspolyamide, such as non-amorphous polyamide 12. In a particular example,the proximal outer layer 54A is a blend of 45% amorphous polyamide 12and 55% non-amorphous polyamide 12. The flexural modulus of the blendmay be about 1000 to about 2000 MPa, or about 1400 to about 1600 MPa. Inanother example, the proximal outer layer 54A is a blend of 60%amorphous polyamide 12 and 40% non-amorphous polyamide 12. The flexuralmodulus of the blend may be about 1000 to about 2000 MPa, or about 1400to about 1600 MPa.

In some embodiments, the distal outer layer 54B may be a blend ofpolyether block amide resins. For instance, the distal outer layer 54Bmay be a blend of about 40% to about 80% by weight of a polyether blockamide having a Shore durometer hardness of about 60D to about 80D, andabout 20% to about 60% by weight of a polyether block amide having aShore durometer hardness of about 50D to about 65D. In some embodiments,the flexural modulus of the blend may be about 300 to about 500 MPa. Ina particular example, the distal outer layer 54B is a blend of 75% of apolyether block amide having a Shore durometer hardness of about 70D and25% of a polyether block amide having a Shore durometer hardness ofabout 55D. The flexural modulus of the blend may be about 400 MPa. Inanother example, the distal outer layer 54B is a blend of 40% of apolyether block amide having a Shore durometer hardness of about 70D and60% of a polyether block amide having a Shore durometer hardness ofabout 63D. The flexural modulus of the blend may be about 390 MPa. Theproximal section 50A and the distal section 50B may be separatelymanufactured, such as by co-extrusion, and then joined together with apolymeric sleeve as described herein.

A method of joining the proximal section 50A and the distal section 50Bof the inner tubular member 50 in a longitudinal, end-to-end orientationutilizing a sleeve overlying a portion of each of the proximal section50A and the distal section 50B will now be described in conjunction withFIGS. 4-8. However, it is noted that other joining orientations of theproximal section 50A and the distal section 50B of the inner tubularmember 50 may benefit from the disclosed joining method.

As shown in FIG. 4, the proximal section 50A and the distal section 50Bmay be placed end-to-end in an abutting relationship, such that thedistal end 51 of the proximal section 50A abuts the proximal end 53 ofthe distal section 50B at joint 65. The joint 65 may be a butt joint asshown throughout the present description, however, in some embodimentsthe joint may alternatively be an overlapping joint, a tapering joint,or the like. The distal end 51 of the proximal section 50A may be incontact with the proximal end 53 of the distal section 50B, or, in someembodiments, a small space or gap may remain between the ends 51, 53. Insome embodiments, a mandrel, such as a polytetrafluoroethylene (e.g.,Teflon) coated mandrel, may be inserted through the lumen 34 of theproximal section 50A and the distal section 50B. The sections 50A, 50Bmay be slid over the mandrel, which may provide interior support tomaintain the structure of the tubular member 50 and preserve the patencyof the tubular lumen 34 throughout the manufacturing process.

The tubular sections 50A, 50B may be appropriately sized as known in theart. For example, in some embodiments the proximal section 50A may havean outer diameter of about 0.01 to about 0.05 inches, or about 0.02 toabout 0.04 inches, or about 0.02 inches. In some embodiments, theproximal section 50A may have an appropriate inner diameter creating awall thickness of about 0.002 to about 0.005 inches. In someembodiments, the distal section 50B may have dimensions similar to thoseof the proximal section 50A. In some embodiments, the distal section 50Bmay have a distal portion having a reduced diameter, wherein theproximal portion may have dimensions similar to those of the proximalsection 50A and the distal portion may have an outer diameter of about0.01 to about 0.04 inches, or about 0.01 to about 0.03 inches, or about0.01 to about 0.02 inches, and/or an inner diameter creating a wallthickness of about 0.002 to about 0.005 inches. The distal section 50Bmay have a tapered portion between the proximal portion and the distalportion forming a transition between the proximal portion and thereduced diameter distal portion.

Referring to FIG. 5, a sleeve 60, such as a polymeric tubular sleeve,may be placed over the joint 65 between the proximal section 50A and thedistal section 5013. The sleeve 60, which in some embodiments may bepreformed such as by extrusion or drawing, may be slid over the tubularsections 50A, 50B, such that a portion of the sleeve 60 is locatedproximal of the joint 65 and a portion of the sleeve 60 is locateddistal of the joint 65. In other words, the sleeve 60 may be positionedso as to bridge the joint 65 between the tubular sections 50A, 50B,overlying a portion of each of the tubular sections 50A, 50B. In someembodiments, the sleeve 60 may be approximately centered over the joint65. The sleeve 60 may be any desired length. For example, in someembodiments the sleeve 60 may be about 2 to about 20 mm in length, about3 to about 10 mm in length, about 4 to about 6 mm in length, or about 5mm in length.

The sleeve 60 may be appropriately sized. For example, the innerdiameter of the sleeve 60 may be chosen to closely approximate the outerdiameter of the tubular sections 50A, 50B adjacent joint 65. In someembodiments, the sleeve 60 may have a wall thickness of about 0.0002 toabout 0.005 inches, or about 0.0005 to about 0.002 inches, or about0.0002 to about 0.001 inches, or about 0.0005 inches. In someembodiments, the sleeve 60 may be dimensioned so as not to measurablyincrease the outer diameter of the inner tubular member 50 near thejoint 65. Therefore, when bonded to the tubular sections 50A, 50B, thesleeve 60 may not appreciably obstruct the inflation lumen 38.

As illustrated in FIG. 6, a length of tubing, such as a length of heatshrink tubing 70, may then be positioned over the sleeve 60 and aportion of each of the tubular sections 50A, 50B, such that the heatshrink tubing 70 extends beyond the extents of the sleeve 60. In someembodiments, the heat shrink tubing 70 may have a length of about 10 toabout 50 mm, or about 20 to about 40 mm, or about 30 mm.

The heat shrink tubing 70 may be chosen to have a higher meltingtemperature than each of the sleeve 60, the outer layer 54A of theproximal section 50A, and the outer layer 54B of the distal section 50B.For example, the sleeve 60 may be a polymeric material of about 100%polyamide 12 having a melting temperature of about 350° F., the proximalouter layer 54A may be a polymeric blend of amorphous polyamide 12 andnon-amorphous polyamide 12 have a melting temperature of about 350° F.to about 375° F., and the distal outer layer 54B may be a polymericblend of polyether block amide resins have a melting temperature ofabout 340° F. to about 350° F. Thus, in some embodiments, the heatshrink tubing 70 may have a melting temperature greater than 375° F. Insome embodiments, the heat shrink tubing 70 may have a meltingtemperature appreciably greater than 375° F. For example, the heatshrink tubing 70 may have a melting temperature generally greater thanthe greatest melting temperature of the sleeve 60, the outer layer 54Aof the proximal section 50A, and the outer layer 54A of the distalsection 50B. For example, in some embodiments, the melting temperatureof the heat shrink tubing 70 may be at least 1.2 times or more, 1.5times or more, 2 times or more, 2.5 times or more, or 3 times or more ofthe greatest melting temperature of the sleeve 60, the outer layer 54Aof the proximal section 50A, and the outer layer 54A of the distalsection 50B. Generally, the heat shrink tubing 70 may have a meltingtemperature that would not impair or destroy the integrity of the joinedregion of the catheter 10.

Referring to FIG. 7, thermal energy may be applied to the heat shrinktubing 70 such that the heat shrink tubing 70 is contracted around thesleeve 60 and a portion of each of the proximal section 50A and thedistal section 50B. Contraction of the heat shrink tubing 70 may providea compressive force directed radially inward on the sleeve 60 and/or theproximal section 50A and the distal section 50B. The compressive forceexerted by the heat shrink tubing 70 may secure the sleeve 60 and thesections 50A, 50B of the tubular member 50 in a desired orientation, andassist in bonding the sleeve 60 to each of the proximal section 50A andthe distal section 50B of the tubular member 50. The heat shrink tubing70 may provide sufficient force to fix the proximal section 50A and thedistal section 50B, forming a smooth transition between the proximalsection 50A and the distal section 50B without generating excess flow ofmaterial from the bond site. The heat shrink tubing 70 may be selectedto generate a high level of compressive force through contraction of theheat shrink tubing 70 when subjected to heat. In some embodiments, theheat shrink tubing 70 may be selected to exert a compressive force ofabout 20 grams or greater, about 25 grams or greater, or about 30 gramsor greater on the underlying sleeve 60. In some embodiments, thecompressive force may be about 25 to about 32 grams.

Concurrently, or in a subsequent step, thermal energy may be applied tothe sleeve 60, the proximal section 50A of the tubular member 50 and/orthe distal section 50B of the tubular member 50. The thermal energy mayelevate the temperature of the sleeve 60, the proximal section 50A,and/or the distal section 50B in order to induce bonding of the sleeve60 to each of the proximal section 50A and the distal section 50B. Forexample, the applied thermal energy may elevate the temperature of thesleeve 60, the portion of the outer layer 54A of the proximal section50A underlying the sleeve 60, and/or the portion of the outer layer 54Bof the distal section 50B underlying the sleeve 60 at or above itsrespective melt temperature. The combination of the compressive forcegenerated by the heat shrink tubing 70 and the thermal energy heatingthe materials above their respective melt temperature may bond thesleeve 60 to each of the proximal section 50A and the distal section50B. The high level of compressive force generated by the heat shrinktubing 70 may facilitate enhanced bonding of the materials. In someembodiments, the materials of the outer layers 54A, 54B and the sleeve60 may be melt compatible or melt miscible. Thus, the materials of theproximal outer layer 54A, the distal outer layer MB, and/or the sleeve60 may blend or mix together to form a strong bond. In some embodiments,ionic bonds, covalent bonds, and/or chain entanglements may be formedbetween the sleeve 60 and each of the proximal section 50A and thedistal section 50B.

Thermal energy may be applied by a laser welding process using a laser80, such as a YAG laser, a CO₂ laser, a diode laser, etc., or anycombination thereof. Typically, a CO₂ laser operated at 10.6 micronsproduces thermal energy which may be readily absorbed by many polymericmaterials. Laser energy typically heats a workpiece from the outsidesurface to the inside. Thus, thermal energy created by a laser, such asa CO₂ laser, may elevate the temperature of the outer layers of materialwithout significantly elevating the temperature of inner layers. Forexample, the use of a CO₂ laser may heat the sleeve 60 and the outerlayers 54A, 54B of the inner tubular member 50 to a temperature at orabove their respective melting temperatures, without heating the innerlayer 52A, 52B and/or the intermediate layer 56A, 56B above itsrespective melting temperature. Thus, the heat affected zone created bythe laser may be limited to the interface between the sleeve 60 and theouter surface of each of the outer layers 54A, 54B of sections 50A, 50Bunderlying the sleeve 60. Therefore, the tubular sections 50A, 50B maybe joined together with the sleeve 60 without adversely affecting thedimensions or integrity of the tubular sections 50A, 50B. Additionalsources of applying thermal energy which may be used include RF heating,electromagnetic induction heating, hot jaw clamping, or the like.

In some embodiments, the path of the laser 80 may be controlled in orderto apply an appropriate amount of thermal energy to select portions ofthe assembly. Due to the different melting temperatures of thecomponents of the assembly, different amounts of thermal energy may beapplied to different portions of the assembly. For example, a largeramount of thermal energy may be applied to the proximal section 50A andthe associated portion of the sleeve 60 overlying the proximal section50A than may be applied to the distal section 50B and the associatedportion of the sleeve 60 overlying the distal section 50B. This may beaccomplished by varying the power of the laser 80, varying the speed oftravel of the laser 80 and/or making additional passes with the laser 80through select portions.

As shown in FIG. 7, the path of the laser 80 may begin at anintermediate location A of the heat shrink tubing 70 proximate the joint65 between the proximal section 50A and the distal section 50B. Thelaser 80 may then travel in the proximal direction B toward the proximalend of the sleeve 60 and the heat shrink tubing 70. The laser 80 maythen reverse directions and travel in the distal direction C toward thedistal end of the sleeve 60 and the heat shrink tubing 70. The laser 80may emit more thermal energy along the proximal path AB between thejoint 65 and the proximal end of the sleeve 60 and the heat shrinktubing 70 than on the distal portion of the path AC between the joint 65and the distal end of the sleeve 60 and the heat shrink tubing 70. Thismay be accomplished by increasing the power of the laser 80 and/ordecreasing the speed of travel of the laser 80 through path AB, forexample.

In some embodiments, the laser may be initially positioned at theintermediate location A proximate the joint 65. The laser 80 may travelin the proximal direction toward location B and the proximal end of theheat shrink tubing 70 while emitting high power. The laser 80 may thenemit low power through the return path from location B to location A.The laser 80 may again emit high power as the laser moves distally fromthe intermediate location A proximate the joint 65 toward the distallocation C and the distal end of the heat shrink tubing 70. Thus, theproximal portion of the assembly located between the joint 65 and theproximal end of the sleeve 60 may be exposed to higher levels of thermalenergy than the distal portion of the assembly located between the joint65 and the distal end of the sleeve 60.

In other embodiments, the laser 80 may follow a different selectedpathway. In some embodiments, the laser 80 may begin proximate one endof the assembly and travel toward the other end of the assembly. In someembodiments, the laser 80 may emit more thermal energy on the portion ofthe assembly proximal of the joint 65 than on the portion of theassembly distal of the joint 65. Such changes in the amount of thermalenergy applied to a specific portion of the assembly may be controlledby varying the power of the laser and/or varying the speed of the laserthrough specific locations, for example.

In some embodiments, the laser 80 may use closed loop control ontemperature in order to precisely and accurately control the elevatedtemperature of components throughout the bonding process. For example,infrared (IR) feedback technology may be used to monitor the temperatureof the components of the assembly. Thus, the laser 80 using IR feedback,or other closed loop control, may precisely elevate the temperature of aspecific location at or above a desired predetermined temperature, suchas the melting temperature of the polymeric materials of the specificlocation. Therefore, IR feedback technology, or other closed looptemperature control, may precisely control the energy level and/or thespeed of the laser 80 in order to elevate each portion of the assemblyto a desired temperature to induce sufficient bonding of the materials.

Now referring to FIG. 8, the heat shrink tubing 70 may then be removedfrom the tubular member 50, leaving the sleeve 60 securely bonded toboth the proximal section 50A and the distal section 50B of the tubularmember 50. The heat shrink tubing 70 may include a slit, notch, groove,perforations, weakened regions, or the like to facilitate removal of theheat shrink tubing from the assembly.

The sleeve 60 may bridge the joint 65 between the proximal section 50Aand the distal section 50B, joining the two sections together. Thecompressive force of the heat shrink tubing 80 may sufficiently compressthe sleeve 60 to a reduced outer diameter, thus not appreciablyenlarging the outer diameter of the inner tubular member 50. Therefore,the sleeve 60 may not obstruct the inflation lumen 38 defined betweenthe outer surface of the inner tubular member 50 and the inner surfaceof the outer tubular member 40 as shown in FIG. 2.

FIG. 9 is a cross-sectional view of the inner tubular member 50,including the sleeve 60 securely bonded to both the proximal section 50Aand the distal section 50B. In some embodiments, the sleeve 60 may besecurely bonded to both the proximal section 50A and the distal section50B, while the ends 51, 53 of the proximal section 50A and the distalsection 50B may remain unbonded to one another. This may be due to thefocused heating emitted by the laser. The focused beam of the laser maylimit the heat affected zone to only the sleeve 60 and the portion ofthe outer layer of the tubular members 54A, 54B underlying the sleeve60. In some embodiments, a small gap or space may be located between thedistal end 51 of the proximal section 50A and the proximal end 53 of thedistal section 50B during the thermal bonding process.

Therefore, a longitudinal force typically used to bond the ends of twotubular sections together at a butt joint using RF energy is notnecessary with the currently presented joining method. A longitudinalforce may adversely affect the dimensions of a tubular member near thejoint. As the ends of the tubular members are softened through heating,the longitudinal compressive force may deform or warp the ends of thetubular members, exceeding the tight dimensional tolerances necessary inmany applications. Pooling of molten polymer material at the jointbetween two tubular sections may also be reduced or eliminated with thepresently presented joining method.

The currently presented joining method, utilizing a polymeric sleeve andheat shrink tubing having high compressibility properties, maintains thetight dimensional tolerances necessary in many applications. Therefore,consistent results may be obtained through the currently presentedmethod. The sleeve 60 forms a strong bond between each of the tubularsections 50A, 50B. The surface area of the bonding regions between thesleeve 60 and the tubular sections 50A, 50B is much greater thanprevious methods of bonding two sections with a butt joint without asleeve.

Although the above method was herein described regarding an innertubular member of a catheter shaft, the invention is not so restricted.It is contemplated that the method may be used in order to securely bondtwo sections of a multi-sectioned tubular member of any elongate medicaldevice.

Those skilled in the art will recognize that the present invention maybe manifested in a variety of forms other than the specific embodimentsdescribed and contemplated herein. Accordingly, departure in form anddetail may be made without departing from the scope and spirit of thepresent invention as described in the appended claims.

1. (canceled)
 2. A catheter comprising: a first tubular member having an inner layer, an outer layer, and an intermediate layer interposed between the inner and outer layers; a second tubular member having an inner layer, an outer layer, and an intermediate layer interposed between the inner and outer layers; wherein an end surface of the first tubular member and an end surface of the second tubular member abut in an end-to-end longitudinal orientation; and a polymeric sleeve comprising a polymeric material having highly oriented molecular chains disposed about the first and second tubular members, such that the sleeve extends over a portion of the first tubular member and a portion of the second tubular member; wherein the polymeric sleeve is laser bonded to each of the first tubular member and the second tubular member such that the abutting end surfaces of the first and second tubular members are not bonded together.
 3. The catheter of claim 2, wherein the outer layer of the first tubular member has a flexural modulus and the outer layer of the second tubular member has a flexural modulus different from that of the outer layer of the first tubular member.
 4. The catheter of claim 3, wherein the flexural modulus of the outer layer of the second tubular member is about 75% less than or more than 75% less than the flexural modulus of the outer layer of the first tubular member.
 5. The catheter of claim 2, wherein the outer layer of the first tubular member comprises a polymeric blend of an amorphous polyamide and a non-amorphous polyamide, the outer layer of the second tubular member comprises a polymeric blend of a first polyether block amide having a Shore durometer hardness and a second polyether block amide having a Shore durometer hardness different from the Shore durometer hardness of the first polyether block amide, and the sleeve comprises a polyamide
 12. 6. The catheter of claim 2, wherein the sleeve comprises a polymeric material having longitudinally oriented molecular chains.
 7. The catheter of claim 2, wherein the sleeve comprises a polymeric material having circumferentially oriented molecular chains.
 8. The catheter of claim 2, wherein the sleeve comprises a polymeric material having helically oriented molecular chains.
 9. The catheter of claim 2, wherein the polymeric sleeve is thermally bonded to each of the first tubular member and the second tubular member.
 10. The catheter of claim 9, wherein the polymeric sleeve is laser bonded to each of the first tubular member and the second tubular member.
 11. An elongate medical device having a proximal end and a distal end, the elongate medical device comprising: an outer tubular member having a proximal end, a distal end, and a lumen extending therethrough; an inner tubular member having a proximal end, a distal end and a lumen extending therethrough, the inner tubular member disposed in the lumen of the outer tubular member; wherein the inner tubular member includes a proximal segment, a distal segment abutting the proximal segment, and a polymeric sleeve extending over and coupling the proximal segment with the distal segment; and an inflatable member affixed to the distal end of the outer tubular member.
 12. The elongate medical device of claim 11, further comprising a guidewire port formed in the outer tubular member proximal of the inflatable member and distal of the proximal end of the elongate medical device, wherein the inner tubular member extends from a distal opening proximate the distal end of the elongate medical device to the guidewire port, thereby defining a guidewire lumen extending from the guidewire port to the distal opening of the elongate medical device.
 13. The elongate medical device of claim 11, wherein the proximal segment of the inner tubular member comprises a first material, the distal segment of the inner tubular member comprises a second material different from the first material, and the sleeve comprises a third material different from the first and second materials.
 14. The elongate medical device of claim 13, wherein the first material comprises a polymeric blend of an amorphous polyamide and a non-amorphous polyamide, the second material comprises a polymeric blend of a first polyether block amide having a Shore durometer hardness and a second polyether block amide having a Shore durometer hardness different from the Shore durometer hardness of the first polyether block amide, and the third material comprises a polyamide
 12. 15. The elongate medical device of claim 11, wherein the proximal segment of the inner tubular member comprises an inner layer, an outer layer, and an intermediate layer interposed between the inner and outer layers, and the distal segment of the inner tubular member comprises an inner layer, an outer layer, and an intermediate layer interposed between the inner and outer layers.
 16. The elongate medical device of claim 11, wherein the sleeve comprises a polymer having highly oriented molecular chains.
 17. The elongate medical device of claim 16, wherein the molecular chains are highly oriented in a longitudinal direction.
 18. The elongate medical device of claim 16, wherein the molecular chains are highly oriented in a circumferential direction.
 19. The elongate medical device of claim 16, wherein the molecular chains are highly oriented in a helical direction. 